The invention relates to a method for bringing together a basic liquid product and a hardener, with a view to attaining a fast-hardening product.
It also relates to means for performing the method and to the equipment provided with these means.
More particularly, but not exclusively, it applies to the field of applying marks to the ground, particularly for marking roadways.
In this field, methods of distributing paint are known, particularly with the aid of a "airless" circuit, which mainly includes a motor that drives at least one pump that forces the paint contained in a reservoir onto the ground, via a circuit leading to a spray nozzle.
The motor that drives the paint pump may be of any known type, and may for example comprise a hydraulic motor, supplied with a hydraulic circuit including a pump of variable output that takes oil from a reservoir and carries it to the hydraulic motor, after passage first via a connection with a safety valve and then via a pressure reducer/regulator and optionally an output reducer that prevents racing of the motor and/or a flow meter that is for example connected to a computer in order to determine the painting output as a function of the ratio of the two circuits.
The oil pump in turn is driven by any known means, particularly a diesel engine.
The assembly including these means is generally mounted on the chassis of a vehicle.
The characteristics of the nozzle and its height from the ground determine the width to which the paint is deposited.
The output of the nozzle and the forward speed of the vehicle, in turn, determine the thickness of the layer of paint deposited.
By interrupting the output of the nozzle, which is done with the aid of a controlled valve placed upstream of the nozzle, the limits of the marks to be made are determined.
Besides the nozzle that sprays the paint, the vehicle generally includes a distributor for fillers such as retroreflective ballotini and/or sand.
So that traffic will be interrupted for as brief a time as possible, the paint must dry very rapidly, and to this end it is known to make use of a hardener.
Until now, this hardener has been in the form of a powder distributed in the manner of the fillers, or even jointly with them.
Hence it only reaches the surface of the layer of paint.
This method of bringing together the basic product and the hardener does not permit uniform mixing and hence does not permit uniform drying of the paint.
Furthermore, it spoils the colors that the paint comes in.
For bringing together two basic liquid products, equipment is known (European Patent 45 536) that in addition to the main circuit includes a secondary circuit with a secondary pump that forces the second liquid product contained in a secondary reservoir along the secondary circuit.
The main circuit and the secondary circuit both lead to the same mixer that supplies the spray nozzle.
In order that the proportions of the mixture to be made are adhered to, the two pumps clearly must have accordingly adjusted outputs, and the actions of the hydraulic circuits are synchronized.
They may also be supplied by the same hydraulic pump.
However, this equipment is unsuitable for bringing together a liquid product and a liquid hardener in order to attain a product that hardens fast enough for painting roads, for example hardening in one minute in the open air at 20.degree. C. or in 30 seconds when air-sealed.
In fact, the mixed product would clearly have enough time to solidify in the mixer during breaks in the spraying, which would make this mixer unusable.
Furthermore, the proportions of hardener with respect to the base are quite low, for example being only 1-2%, and so the output of the hardener circuit would be low, and its low speed and the constancy of pressure that the pump would communicate to the hardener would rapidly cause the liquid and solid portions to separate, rendering this hardener unusable.
One object that the invention seeks to obtain is a method for bringing together a base and a hardener that assures a uniform mixture of the product obtained and that does not affect the colors that the product comes in.
Another object that the invention seeks to obtain is a method that assures that the distributor means cannot become clogged and that the hardener will remain usable for a very long time.
To this end, the subject of the invention is a method of the aforementioned type, by which method the secondary reservoir is supplied with the liquid hardener that the secondary product circuit brings to the mixer, which mixes it with the base prior to carrying the mixture to the spray nozzle, and upon completion of the spraying, the feeding of both the base and the hardener to the mixer is interrupted, and an evacuation and cleaning cycle is triggered, during which evacuation and cleaning cycle the return of the hardener to its reservoir is controlled in such a way as to recirculate it, this method being characterized in particular in that:
upon the interruption of the spraying, a circuit for adjusted delay is activated for a period of time between a zero value and a value at least slightly less than the hardening time when air-sealed; PA1 and the end of the predetermined period of time, with the aid of this delay circuit, a signal is emitted, with the aid of which: PA1 the feeding of the base (1) and hardener to the mixer is interrupted, and PA1 the evacuation and cleaning cycle is triggered, including, in particular, alternating phases of washing, using at least one solvent, and rinsing, during which cleaning cycle the aforementioned return of the hardener to its reservoir is controlled in such a way as to recirculate it.
The subject is also the means for performing this method and the equipment provided with these means.